Degradation of light carrying orbital angular momentum by ballistic scattering

Structured light can enhance the functionality of optical communication and sensing systems. Dense scattering environments such as those experienced in coastal water or foggy conditions result in degradation of structured optical fields. We present findings that characterise the degradation of the phase structure of ballistic scattered light carrying Orbital Angular Momentum (OAM) propagated through a dense scattering medium over distances of up to 20m. We present a numerical
channel modelling approach that can predict the scattering behaviour at extended distances, which indicates that there is a strong mode dependent variance in crosstalk from the interaction of beams that carry OAM with randomly displaced scattering particles. These results present a novel effect that could allow the use of OAM modes to enhance particulate size sensors and could potentially lead to the development of novel tools for monitoring particles in underwater or free-space optical channels.